This invention relates to stripe lasers.
According to the present invention there is provided an injection laser in which current flow across the active layer is restricted by confining the current flow across an adjacent interface, wherein the current across said interface is confined to a pair of closely spaced parallel stripes dimensioned and spaced so as to promote the waveguiding of the zero order mode of the laser in preference to the waveguiding of the first order mode and waveguiding by the so called "gain guiding" mechanism. The interface may be that between a top electrical contact layer and underlying epitaxially grown semiconductive material. Alternatively it may be between a semiconductive substrate and epitaxially grown semiconductive material underlying the active layer.
The invention also provides a method of making an injection laser including the step of providing the laser with an interface adjacent the active layer across which interface the current flow is confined to two parallel stripes dimensioned and spaced so as to promote the real dielectric waveguiding of the zero order mode of the laser in preference to either gain-guiding or to the waveguiding of the first order mode.
This twin stripe arrangement produces a carrier density distribution that is more suited to optical guiding than that produced by the single strip of a conventional stripe laser. This, in turn, reduces the recurrent problem in conventional stripe lasers of optical instability which causes non-linear light/current characteristics and excess noise.
In the following description a heterostructure Ga.sub.(1-x) Al.sub.(x) As (x.gtoreq.0) stripe contact laser constructed in accordance with the present invention is contrasted with a conventional stripe contact laser.